Multifunction Phased Array Radar (MPAR) is a multiagency initiative to reduce risk associated with designing one type of phased array radar to replace the seven models of mechanically rotating conventional radars currently operated by four Federal agencies. The effort investigates the potential for sharing data from approximately 330 multifunction radars, which would replace about 510 single-purpose installations. The Office of the Federal Coordinator for Meteorological Services and Supporting Research (OFCM) sponsors the Working Group for MPAR and the MPAR Executive Council. The Unified Research and Development Plan (R&D Plan) comprises two major components which together address the three key risk reduction issues. Technology Development and Test addresses the dual polarization and cost reduction, and Proof of Operational Concepts addresses multifunctionality. The individual research elements within the major components are prioritized, and a measure of risk is assigned to each element. Some effort was made to align the research elements with the various risk reduction initiatives underway or planned in the R&D community.